Processes for making a super-insulating core for a vacuum insulating structure

ABSTRACT

A method for forming a super-insulating material for a vacuum insulated structure for an appliance includes disposing hollow glass spheres within a rotating drum, wherein a plurality of interstitial spaces are defined between the hollow glass spheres. An anchor material is disposed within the rotating drum. The hollow glass spheres and the anchor material are rotated within the rotating drum, wherein the anchor material is mixed with the hollow glass spheres to partially occupy the interstitial spaces. A silica-based material is disposed within the rotating drum. The silica-based material is mixed with the anchor material and the hollow glass spheres to define a super-insulating material, wherein the silica-based material attaches to the anchor material and is entrapped within the interstitial spaces. The silica-based material and the anchor material occupy substantially all of an interstitial volume defined by the interstitial spaces.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a divisional of U.S. patent application Ser.No. 16/308,531 filed Dec. 10, 2018, entitled PROCESSES FOR MAKING ASUPER-INSULATING CORE FOR A VACUUM INSULATING STRUCTURE, which is anational stage of International Application No. PCT/US2016/054067 filedSep. 28, 2016, entitled PROCESSES FOR MAKING A SUPER-INSULATING CORE FORA VACUUM INSULATING STRUCTURE, the entire disclosures of which arehereby incorporated herein by reference.

FIELD OF THE DEVICE

The device is in the field of insulating materials for appliances, andmore specifically, various processes for making super-insulating corematerials that can be included within vacuum insulated structures forvarious appliances.

SUMMARY

In at least one aspect, a method for forming a super-insulating materialfor a vacuum insulated structure for an appliance includes disposinghollow glass spheres within a rotating drum, wherein a plurality ofinterstitial spaces are defined between the hollow glass spheres. Ananchor material is disposed within the rotating drum. The hollow glassspheres and the anchor material are rotated within the rotating drum,wherein the anchor material is mixed with the hollow glass spheres topartially occupy the interstitial spaces. A silica-based material isdisposed within the rotating drum. The silica-based material is mixedwith the anchor material and the hollow glass spheres to define asuper-insulating material, wherein the silica-based material attaches tothe anchor material and is entrapped within the interstitial spaces. Thesilica-based material and the anchor material occupy substantially allof an interstitial volume defined by the interstitial spaces.

In at least another aspect, a method for forming a super-insulatingmaterial for a vacuum insulated structure for an appliance includesdisposing glass spheres within a rotating drum, wherein a plurality ofinterstitial spaces are defined between the glass spheres. A coatingmaterial is disposed within the rotating drum. The glass spheres and thecoating material are mixed to define an adhering base material, whereinthe interstitial spaces of the glass spheres are partially occupied bythe coating material. A silica-based material is disposed within therotating drum. The silica-based material is mixed with the glass spheresand the coating material to define a super-insulating material, whereinthe silica-based material adheres to the glass spheres via the coatingmaterial, wherein the coating material and the silica-based materialoccupy substantially all of an interstitial volume defined by theinterstitial spaces.

In at least another aspect, a method for forming a super-insulatingmaterial for a vacuum insulated structure for an appliance includesdisposing a process fluid in a rotating drum, disposing a silica-basedmaterial into the fluid within the rotating drum to form a silica-basedliquid, disposing glass spheres within the silica-based liquid, mixingthe glass spheres with the silica-based liquid and removing at least aportion of the fluid from the silica-based liquid. The silica-basedmaterial adheres to the glass spheres to define silica-coated spheres toform a super-insulating material, wherein a surface of the silica-coatedspheres is indicative of the silica-based material.

In at least another aspect, a method for forming a super-insulatingmaterial for a vacuum insulated structure for an appliance includesdisposing a silica-based material into a mixing drum, wherein the mixingdrum includes at least one mixing impeller. An opacifier is disposedinto the mixing drum, wherein the silica-based material is mixed withthe opacifier. A granulation fluid is disposed into the mixing drum,wherein the granulation fluid is combined with the silica-based materialand the opacifier. A first fluid portion of the granulation fluid isremoved from the mixing drum, wherein a second fluid portion of thegranulation fluid bonds with the silica-based material to define adensified silica-based mixture.

These and other features, advantages, and objects of the present devicewill be further understood and appreciated by those skilled in the artupon studying the following specification, claims, and appendeddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a front perspective view of an appliance incorporating avacuum insulated structure made according to at least one aspect of aprocess for making a super-insulating core material for a vacuuminsulated structure;

FIG. 2 is a perspective view of an aspect of a super-insulating materialmade using glass spheres and an anchor material, and exemplifying a stepof the process before a silica-based material is added thereto;

FIG. 3 is a schematic cross-sectional view of the super-insulatingmaterial of FIG. 2 with the silica-based material added to the rotatingdrum;

FIG. 4 is a perspective view of an aspect of a super-insulating materialmade according to a method for an anchor material that is also aninsulating material;

FIG. 5 is an alternate perspective view of the super-insulating materialof FIG. 4 ;

FIG. 6 is a perspective view of the super-insulating material of FIG. 4illustrating the attachment of the silica-based material with theinsulating anchor material;

FIG. 7 is a schematic cross-sectional view of the super-insulatingmaterial of FIG. 6 showing the silica-based material held in place bythe insulating anchor material;

FIG. 8 is an aspect of the super-insulating material made according to aprocess that includes a coating material disposed on surfaces of theinsulating glass spheres;

FIG. 9 is a perspective view of the super-insulating material madeaccording to a process that includes a coating material disposed onsurfaces of the insulating glass spheres;

FIG. 10 is a schematic diagram illustrating a method for using a methodof precipitation for attaching a silica-based material to a glasssphere;

FIG. 11 is a perspective view of a coated glass sphere made according tothe method exemplified in FIG. 10 ;

FIG. 12 is a schematic cross-sectional view of a mixing drum used toformulate an aspect of the super-insulating material;

FIG. 13 is a schematic diagram illustrating a method of wet granulationto form a densified silica-based mixture;

FIG. 14 is a schematic diagram illustrating an aspect of the methodexemplified in FIG. 13 showing partial fragmentation of the densifiedsilica-based mixture according to at least one milling process;

FIG. 15 is a schematic diagram exemplifying further milling processes ofthe densified silica-based mixture;

FIG. 16 is a schematic diagram illustrating further milling processes ofthe densified silica-based mixture for forming an aspect of thesuper-insulating material;

FIG. 17 is a schematic flow diagram illustrating a method for forming asuper-insulating material for a vacuum insulated structure;

FIG. 18 is a schematic flow diagram illustrating a method for forming asuper-insulating material for a vacuum insulated structure;

FIG. 19 is a schematic flow diagram illustrating a method for forming asuper-insulating material for a vacuum insulated structure; and

FIG. 20 is a schematic flow diagram illustrating a method for forming asuper-insulating material for a vacuum insulated structure.

DETAILED DESCRIPTION OF EMBODIMENTS

For purposes of description herein the terms “upper,” “lower,” “right,”“left,” “rear,” “front,” “vertical,” “horizontal,” and derivativesthereof shall relate to the device as oriented in FIG. 1 . However, itis to be understood that the device may assume various alternativeorientations and step sequences, except where expressly specified to thecontrary. It is also to be understood that the specific devices andprocesses illustrated in the attached drawings, and described in thefollowing specification are simply exemplary embodiments of theinventive concepts defined in the appended claims. Hence, specificdimensions and other physical characteristics relating to theembodiments disclosed herein are not to be considered as limiting,unless the claims expressly state otherwise.

As illustrated in FIGS. 1-20 , reference numeral 10 generally refers toa super-insulating material formed according to various processes usedto form a core material 12 for a vacuum insulated structure 14.According to the various embodiments, the core material 12 can be formedthrough various methods and then disposed within an insulating cavity 16of an insulating structure 18. It is contemplated that after formationor substantial formation of the super-insulating material 10, thatmaterial can be disposed within the insulating cavity 16. Where thematerial is sufficiently dense, and includes minimal gaseous pores 44,the insulating structure 18 can be sealed to form the insulatingstructure 18 having the core of super-insulating material 10 disposedtherein.

Typically, additional steps of expressing gas 20 from the insulatingcavity 16 having the super-insulating material 10 disposed therein isconducted. According to the various embodiments, the expression of gas20 from the insulating cavity 16 defines an at least partial vacuumwithin the insulating cavity 16 of the insulating structure 18. It iscontemplated that according to the various aspects of the process forforming the super-insulating material 10, the super-insulating material10 is sufficiently dense and has a sturdy structure that substantiallyresists compression. Accordingly, minimal vacuum bow or inwarddeformation of the insulating structure 18 is experienced during gasexpression or other gas expulsion processes. The super-insulatingmaterial 10, when disposed within the insulating cavity 16, has a robuststructure and density that serves to resist the inward force resultingfrom a pressure differential between the at least partial vacuum withinthe insulating cavity 16 and the atmospheric pressure outside of theinsulating structure 18. Once gas 20 is expressed from the insulatingcavity 16, the insulating structure 18 can be sealed to define thevacuum insulated structure 14, such as a vacuum insulated cabinet orvacuum insulated panel, that is used to insulate various appliances 22.These appliances 22 can include, but are not limited to, refrigerators,freezers, coolers, hot water heaters, ovens, laundry appliances,dishwashers, and other similar appliances 22 in both commercial andhousehold settings. The term “expressed” is used to describe the removalof gas 20 from within the insulating cavity 16. It is contemplated that“expressed” also includes similar processes that involve the expulsion,suction, compression or other similar removal of gas 20.

Referring again to FIGS. 1-7 and 17 , a method 400 is disclosed forforming a super-insulating material 10 that can be used as a corematerial 12 for a vacuum insulated structure 14 for an appliance 22.According to the method 400, glass spheres 30, which can include hollowor solid glass spheres, can be placed within a mixing or rotating drum32 (shown in FIG. 12 ) (step 402). It is contemplated that a pluralityof interstitial spaces 34 are defined between the glass spheres 30disposed within the drum 32. An anchor material 36 is also disposedwithin the drum 32 (step 404). According to the various embodiments, itis contemplated that the anchor material 36 can include various organicand/or inorganic materials. These anchor materials 36 can include, butare not limited to, glass fiber 60, powdered perlite 70, other forms ofperlite 70, fibrous micro-sized materials, fibrous nano-sized materials,combinations thereof, and other similar anchor materials 36 that can beused to retain an insulating material within the interstitial spaces 34between the glass spheres 30. It is also contemplated that the anchormaterial 36 can also be a secondary insulating material 38, such as inthe case of perlite 70 and/or diatomaceous earth powder, which can haveindependent insulating properties.

Referring again to FIGS. 1-7 and 17 , the hollow glass spheres 30 andthe anchor material 36 can be rotated or otherwise mixed within the drum32. In this manner, the anchor material 36 is mixed with the hollowglass spheres 30, such that the anchor material 36 at least partiallyoccupies the interstitial spaces 34. According to the method 400, asilica-based material 40 is disposed within the drum 32 (step 408). Theanchor material 36 that is intertwined within the hollow glass spheres30 along with the silica-based material 40 are mixed to define thesuper-insulating material 10. It is contemplated that the silica-basedmaterial 40 attaches to the anchor material 36 or is retained by theanchor material 36 and is entrapped within the interstitial spaces 34between the hollow glass spheres 30 and within the anchor material 36(step 410). It is contemplated that the silica-based material 40 and theanchor material 36 occupy substantially all of the interstitial volume42 defined by the interstitial spaces 34 between the hollow glassspheres 30. According to the various embodiments, it is contemplatedthat the silica-based material 40 can be fumed silica, precipitatedsilica, granular aerogels, micro/nano hollow organic and inorganicspheres, rice husk ash, various opacifiers 142, fibrous insulatingmaterial, combinations thereof and other similar insulating materialsthat can be mixed into the interstitial spaces 34 between the glassspheres 30 and the anchor material 36. Through this process, the size ofthe various gaseous pores 44 that are defined between the silica-basedmaterial 40, the anchor material 36 and the hollow glass spheres 30 canbe kept to a minimal size, and typically less than one micron.Additionally, it is contemplated that the hollow glass spheres 30 caninclude nanospheres, microspheres, and combinations thereof. The hollowglass spheres 30 can also include an interior space 46 that is filledwith an insulating gas 20 or can be an at least partial vacuum withinthe hollow interior space 46 of the hollow glass sphere 30. Also, solidglass spheres 30 may also be used where hollow glass spheres 30 arenoted.

Referring again to FIGS. 2 and 3 , it is contemplated that the anchormaterial 36, in the form of glass fiber 60, can have a fiber thicknessin a range of 5 microns to approximately 100 microns. It is alsocontemplated that the glass fiber 60 can have a fiber length in a rangeof from approximately 2 millimeters to approximately 10 millimeters.

Typically, hollow glass spheres 30 can have a packing density fromapproximately 50 percent to approximately 74 percent that variesdepending upon the process used to form the hollow glass spheres 30.This corresponds to an interstitial volume 42 of from approximately 50percent to approximately 26 percent. The various interstitial spaces 34within the interstitial volume 42 can have different dimensions andshapes that typically range from approximately 100 nanometers toapproximately 600 microns at different locations of the mixturecontaining the hollow glass spheres 30. These interstitial spaces 34 cancontribute to higher gaseous thermoconnectivity at various pressurelevels, such as approximately from 0.1 milibar to approximately 1000milibar. Significant adverse effects as a result of the interstitialvolume 42 can be seen at a pressure above 1 milibar.

According to the various embodiments, in order to reduce this gaseousconduction and in order to form an aspect of the super-insulatingmaterial 10, the anchor material 36, typically in a form oforganic/inorganic fiber, diatomaceous earth and/or perlite 70 can beintroduced up to approximately 1 percent to approximately 40 percent byvolume to occupy the interstitial volume 42 during a mixing process withthe hollow glass spheres 30. It is contemplated that the mixing processbetween the hollow glass spheres 30 and the anchor material 36 can alsoinclude a single mixing process that includes the silica-based material40 such that one mixing process is used to form the super-insulatingmaterial 10. During the one or more mixing processes, the glass fiber 60can be distributed in the interstitial volume 42, such that the anchormaterial 36 entraps the silica-based materials 40 within theinterstitial volume 42 as well.

As discussed above, the gaseous pores 44 remaining as a result of themixing process leads to a reduction of gaseous conduction and gaseouspores 44 having a size along the order of less than 1 micron. The use ofthe anchor material 36 provides an attachment point for the silica-basedmaterial 40 to hold onto in order to occupy the interstitial volume 42.Additionally, less segregation of the silica-based material 40 from theinterstitial volume 42 will occur as a result of the anchor material 36holding the silica-based material 40 within the interstitial volume 42.

According to the various embodiments, as exemplified in FIGS. 1-7 and 17, where perlite 70 is used as an anchor material 36 for thesuper-insulating material 10, the perlite 70 can include a powder orshale structure that can, similar to the glass fiber 60, entrap thesilica-based material 40 within the interstitial volume 42. Becauseperlite 70 has insulating properties of its own, the use of perlite 70and/or diatomaceous earth powder can be used as the secondary insulatingmaterial 38 to add to the insulating properties of the hollow glassspheres 30 and the silica-based material 40.

Referring now to FIGS. 1, 8, 9 and 18 , a method 500 is disclosed forforming an aspect of the super-insulating material 10 that can beincluded within the vacuum insulating structure 18 for an appliance 22.According to the method 500, hollow and/or solid glass spheres 30 can bedisposed within a rotating and/or mixing drum 32 (step 502). It iscontemplated that, as discussed above, a plurality of interstitialspaces 34 can be defined between the glass spheres 30. A coatingmaterial 80 can be disposed within the drum 32 (step 504). The glassspheres 30 and the coating material 80 can be mixed to define anadhering base material 82 (step 506). According to the variousembodiments, the interstitial spaces 34 between the various glassspheres 30 are at least partially occupied by the coating material 80.The silica-based material 40 can then be disposed within the drum 32(step 508). The silica-based material 40 can then be mixed with theglass spheres 30 and the coating material 80 that defines the adheringbase material 82, such that the adhering base material 82 and thesilica-based material 40 define the super-insulating material 10 (step510). It is contemplated that the silica-based material 40 adheres to anouter surface 84 of the glass spheres 30 via the coating material 80. Itis further contemplated that the coating material 80 and thesilica-based material 40 serve to occupy substantially all of theinterstitial volume 42 defined by the interstitial spaces 34 between theglass spheres 30.

Referring again to FIGS. 8, 9 and 18 , it is contemplated that thecoating material 80 can be in the form of a functional group material90. This functional group materials 90 can serve to alter the magneticcharacteristics of the glass spheres 30. Accordingly, the magneticcharacteristics of the glass spheres 30 can be altered to definepositively charged surfaces of the glass spheres 30. The silica-basedmaterial 40, which typically has a negatively charged character, adheresto the positively charged surfaces of the glass spheres 30. Accordingly,the functional group material 90 serves to adhere, magnetically, thesilica-based material 40 with the glass spheres 30.

It is contemplated that the functional group material 90 can include,but is not limited to, at least one of an amine functional group, anamino functional group, a silanol functional group, and a silanefunctional group, combinations thereof, and other similar functionalgroup materials 90. According to the various embodiments, typically,hollow glass spheres 30 and particles of the silica-based material 40are generally hydrophilic in nature and contain a slightly negativecharge and typically repel one another such that the insulating materialdoes not properly adhere to the glass spheres 30.

Referring again to FIGS. 8 and 9 , the use of the functional groupmaterial 90 alters the magnetic characteristics of the hollow glassspheres 30 to generate a slightly positive charge on the outer surface84 of the hollow glass spheres 30. Accordingly, the now positivelycharged hollow glass spheres 30 attract the negatively chargedsilica-based material 40, such that the majority of the interstitialvolume 42 can be occupied by the silica-based material 40. As discussedabove, the size of the gaseous pores 44 defined between the silica-basedmaterial 40 can be along the order of less than one micron. This smallgaseous pore size leads to lower gaseous conductivity within the corematerial 12 using the super-insulating material 10.

Referring again to FIGS. 8, 9 and 18 , in implementing the method 500,the coating material 80 can also be a binder material 100. It iscontemplated that the binder material 100 can serve to generate anadhesive surface over the glass spheres 30. In such an embodiment, thesilica-based material 40 adheres to the glass spheres 30 via the bindermaterial 100. It is further contemplated that the binder material 100can include an organic and/or inorganic binder. It is also contemplatedthat the binder material 100 can include, but is not limited to,cellulose, wax, polyethylene glycol, gelatin, starch, polyvinyl alcohol,polymethacrylates and sodium silicate, combinations thereof, and othersimilar adhesives and/or binder materials 100.

In using a binder material 100 as the coating material 80, a relativelysmall amount of organic/inorganic binder, along the order ofapproximately 10 percent by weight, can be infused with or coated aroundthe glass spheres 30 during an initial mixing process within the drum32. It is also contemplated that various spray processes using high orlow pressure sprayers can be used to apply the binder before theaddition of the silica-based material 40. The binders used arecompatible with both the outer surface 84 of the glass spheres 30 aswell as the silica-based material 40 from an adhesion standpoint. It iscontemplated that relatively medium to high temperature can also be usedduring the mixing process to ensure that the hollow glass spheres 30 areuniformly coated by the binder material 100. Once the hollow glassspheres 30 are coated, typically after a few minutes of mixing,approximately 20 percent up to approximately 60 percent by volume of thesilica-based material 40 can be added, followed by a subsequent mixingprocess. As discussed above, the binder material 100 facilitates theadhesion of the silica-based material 40 to the outer surface 84 of theglass spheres 30. As with processes previously described, the gaseouspores 44 resulting from this process can have a size of less than 1micron in diameter.

Referring now to FIGS. 10, 11 and 19 , a method 600 is disclosed forforming a super-insulating material 10 for use within a vacuum insulatedstructure 14 for an appliance 22. According to the method 600, a processfluid 110 can be disposed within the mixing and/or rotating drum 32(step 602). The silica-based material 40 is also disposed within thedrum 32 to be combined within the fluid to form a silica-based liquid112 (step 604). The glass spheres 30 can then be disposed within asilica-based liquid 112 (step 606). After addition of the glass spheres30 with the silica-based liquid 112, these components are mixed withinthe drum 32 (step 608). After the glass spheres 30 and the silica-basedliquid 112 are mixed, at least a portion of the process fluid 110 fromthe silica-based liquid 112 is removed (step 610). Removal of at least aportion of the process fluid 110 from the silica-based liquid 112results in the silica-based material 40 being adhered to the glassspheres 30 to define silica-coated spheres 114 that form thesuper-insulating material 10. It is contemplated that the surface of thesilica-coated spheres 114 is indicative of the silica-based material 40.In this manner, when the silica-coated spheres 114 are mixed together,the silica-based material 40 disposed on the glass spheres 30intermingles to form a minimal amount of gaseous pores 44 between thesilica-coated spheres 114.

Referring again to FIGS. 10, 11 and 19 , in various embodiments, wherethe gaseous pores 44 may have a larger size between the silica-coatedspheres 114, a secondary insulating material 38 can be disposed into therotating drum 32 (step 612). It is contemplated that the interstitialspace 34 can be defined between the silica-coated spheres 114 and themixing of the secondary insulating material 38 with the silica-coatedspheres 114 defines the super-insulating material 10. It is contemplatedthat the secondary insulating material 38 can, in such an embodiment,occupy substantially all of an interstitial volume 42 defined by theinterstitial spaces 34 between the silica-coated spheres 114 (step 614).

Referring again to FIGS. 10, 11 and 19 , it is contemplated that theprocess fluid 110 used in method 600 can include various components,where these components can include, but are not limited to, styrene,polyvinyl pyrrolidone, potassium persulfate, tetraethyl orthosilicate,an ammonium hydroxide solution, absolute ethanol, water and oil,combinations thereof, and other similar organic and/or inorganic fluids.It is contemplated that the step of removing the process fluid 110 (step610) can include a chemical process. In this manner, a first portion 120of the process fluid 110 may be removed and a second portion 122 of theprocess fluid 110 serves to bind the silica-based material 40 into theglass spheres 30 to form the silica-coated spheres 114. According to thevarious embodiments, the step 610 of removing the process fluid 110 caninclude an evaporating process where at least a portion of the processfluid 110 from the rotating drum 32 is evaporated, thereby leaving thesilica-coated spheres 114. Additionally, it is contemplated that thesecondary insulating material 38 of step 612 can be a secondsilica-based material 40 or can be the same as the silica-based material40 that is coated on the glass spheres 30.

According to the method 600, particles of the silica-based material 40are precipitated onto the surface of the hollow glass spheres 30, whereporous agglomerates of the silica-based material 40 mixed with thehollow glass spheres 30 exhibit large gaseous pores 44 therebetween.These large gaseous pores 44 can result in significant increase inthermal connectivity when the pressure rises from 1 milibar to 10milibar. Typically, these larger gaseous pores 44 that form theinterstitial spaces 34 are believed to be the result of smooth surfacesof the hollow glass spheres 30. Because the silica-based material 40readily forms amorphous agglomerates that readily aggregate into largerstructures with very small gaseous pores 44, the silica-based material40 coated onto the glass spheres 30 serves to fill the large gaseouspores 44 to result in very small gaseous pores 44 between thesilica-coated spheres 114. As discussed above, these gaseous pores 44can have a size of less than approximately 1 micron. The resultingsilica-coated spheres 114 serve as a super-insulating material 10 sincethe resulting super-insulating material 10 has desirable qualities ofhollow glass spheres 30 such as flowability, density, and resistance tocompaction. This is combined with the low gaseous pore size of themicro-agglomerates of the silica-based material 40. These two materialscombine through the various coating processes of method 600 to form acomposite material that generates the super-insulating material 10 withminimal gaseous voids and better insulating properties.

Referring now to FIGS. 12-16 and 20 , a method 700 is disclosed forforming the super-insulating material 10 for a vacuum insulatedstructure 14 for an appliance 22. According to the method 700, asilica-based material 40 is disposed into a rotating and/or mixing drum32 (step 702). It is contemplated that the drum 32 can include at leastone mixing impeller 140 such as a high shear impeller 140 or potentiallytwin screws for mixing the contents thereof. An opacifier 142 can alsobe disposed within the mixing drum 32 (step 704). It is contemplatedthat a silica-based material 40 is mixed with the opacifier 142. It iscontemplated that the silica-based material 40 and opacifier 142 can bemixed before being transported to the mixing drum 32, or can be mixedwithin the mixing drum 32. According to the method 700, a granulationfluid 144 is disposed into the drum 32, where the granulation fluid 144is combined with the silica-based material 40 and the opacifier 142(step 706). According to the method 700, a first fluid portion 146 ofgranulation fluid 144 is removed from the drum 32, wherein a secondfluid portion 148 of the granulation fluid 144 bonds with a silica-basedmaterial 40 to define a densified silica-based mixture 150 (step 708).At least one milling operation 160 is conducted, wherein at least onemixing impeller 140 granulates the densified silica-based mixture 150 todefine the super-insulating material 10 (step 710).

Referring again to FIGS. 12-16 and 20 , the first fluid portion 146 ofthe granulation fluid 144 can include at least one solvent. The secondfluid portion 148 of the granulation fluid 144 can include a bindingmaterial. It is contemplated that the at least one solvent can includeat least one of water, ethanol, and/or isopropanol. According to thevarious embodiments, it is contemplated that the at least one solventcan be removed during step 708 during the evaporation process. Insteadof an evaporation process, it is contemplated that granulation fluid 144can be disposed in the mixing drum 32 as a steam-injected material. Itis contemplated that the granulation fluid 144 can also be added as amoisture composition and can be alcohol based or can include variousbinders such as wax and other similar forms of polyvinyl pyrollidone(PVP). This second fluid portion 148 of the granulation fluid 144 thatcomprises one or more binders serves to form polar bonds with thesilica-based material 40 to define the densified silica-based mixture150. It is contemplated that the use of PVP can be advantageous as aninsulating component since PVP has been found to be food safe asrecognized by the Food and Drug Administration for many uses. Asdiscussed above, the dissolved PVP serves to form polar bonds with thesilica-based material 40 as the solvent is removed through theperformance of the evaporation and/or other drying process. According tothe various embodiments, the various milling operations 160 of step 710can be conducted until the densified silica-based mixture 150 definesthe desired granule size. It is also contemplated that the millingoperation 160 can include at least one coalescing process 162. In the atleast one coalescing process 162, milled densified silica-based mixture150 can be recombined to form an enlarged densified granules.Accordingly, various densification and coalescing steps can be performedduring the one or more milling operations 160 to achieve precise granulesize of the densified silica-based mixture 150 to form thesuper-insulating material 10.

According to the method 700, the various milling process can be used tooptimize the size, density and intragranular porosity and structuralstability of the densified silica-based mixture 150 as needed to supportthe product design. The densified silica-based material 40 provides agreater resistance to compression, in particular, inward forcesexperienced in the expression of gas 20 from a vacuum insulatedstructure 14.

According to the various methods 400, 500, 600, 700 used to form thevarious aspects of the super-insulating material 10, it is contemplatedthat the various methods can include additional steps of disposing asuper-insulating material 10 into an insulating cavity 16 of aninsulating structure 18. As discussed above, gas 20 can be expressedfrom the insulating cavity 16 to define an at least partial vacuumwithin the insulating cavity 16. Once the partial vacuum is formed, theinsulating cavity 16 can be sealed to define the vacuum insulatingstructure 18. According to the various embodiments, the vacuum insulatedstructure 14 can be defined by a panel 170 where the vacuum insulatedstructure 14 is a vacuum insulated panel. Additionally, the insulatingstructure 18 can take the form of an appliance cabinet 172 made from anouter wrapper 174 and an inner liner 176 that can be attached to definean insulating cavity 16 therein. According to such an embodiment, thevacuum insulated structure 14 can take the form of a vacuum insulatedcavity.

According to the various embodiments, the advantage of the variousprocesses of method 700, which may be referred to as wet granulation, isthat the amount of dust generation can be minimized through the use ofthe granulation fluid 144 that is added to the opacifier 142 andsilica-based material 40 mixture. This dust, in conventional processes,can result in inadvertent inhalation as well as wasted material.

As discussed above, the use of the various processes exemplified inmethods 400, 500, 600 and 700 can be used to form a densifiedsuper-insulating material 10 that can serve to resist the inwardcompressive forces experienced during evacuation of gas 20 and forming avacuum insulated structure 14. The dense nature of the super-insulatingmaterial 10 resists crushing and provides a resistive outward force toprevent inward vacuum bow of the various components of the vacuuminsulated structure 14. Additionally, the various methods 400, 500, 600,700 described herein create a minimal amount and minimal size of gaseouspores 44 of less than one micron within the super-insulating material10. These characteristics provide a better insulating functionality forthe vacuum insulated structure 14.

It will be understood by one having ordinary skill in the art thatconstruction of the described device and other components is not limitedto any specific material. Other exemplary embodiments of the devicedisclosed herein may be formed from a wide variety of materials, unlessdescribed otherwise herein.

For purposes of this disclosure, the term “coupled” (in all of itsforms, couple, coupling, coupled, etc.) generally means the joining oftwo components (electrical or mechanical) directly or indirectly to oneanother. Such joining may be stationary in nature or movable in nature.Such joining may be achieved with the two components (electrical ormechanical) and any additional intermediate members being integrallyformed as a single unitary body with one another or with the twocomponents. Such joining may be permanent in nature or may be removableor releasable in nature unless otherwise stated.

It is also important to note that the construction and arrangement ofthe elements of the device as shown in the exemplary embodiments isillustrative only. Although only a few embodiments of the presentinnovations have been described in detail in this disclosure, thoseskilled in the art who review this disclosure will readily appreciatethat many modifications are possible (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter recited. For example,elements shown as integrally formed may be constructed of multiple partsor elements shown as multiple parts may be integrally formed, theoperation of the interfaces may be reversed or otherwise varied, thelength or width of the structures and/or members or connector or otherelements of the system may be varied, the nature or number of adjustmentpositions provided between the elements may be varied. It should benoted that the elements and/or assemblies of the system may beconstructed from any of a wide variety of materials that providesufficient strength or durability, in any of a wide variety of colors,textures, and combinations. Accordingly, all such modifications areintended to be included within the scope of the present innovations.Other substitutions, modifications, changes, and omissions may be madein the design, operating conditions, and arrangement of the desired andother exemplary embodiments without departing from the spirit of thepresent innovations.

It will be understood that any described processes or steps withindescribed processes may be combined with other disclosed processes orsteps to form structures within the scope of the present device. Theexemplary structures and processes disclosed herein are for illustrativepurposes and are not to be construed as limiting.

It is also to be understood that variations and modifications can bemade on the aforementioned structures and methods without departing fromthe concepts of the present device, and further it is to be understoodthat such concepts are intended to be covered by the following claimsunless these claims by their language expressly state otherwise.

The above description is considered that of the illustrated embodimentsonly. Modifications of the device will occur to those skilled in the artand to those who make or use the device. Therefore, it is understoodthat the embodiments shown in the drawings and described above is merelyfor illustrative purposes and not intended to limit the scope of thedevice, which is defined by the following claims as interpretedaccording to the principles of patent law, including the Doctrine ofEquivalents.

What is claimed is:
 1. An insulated structure for an appliance, theinsulated structure comprising: an inner liner and an outer wrapper thatare attached together to define an insulating cavity therein; aplurality of glass spheres disposed within the insulating cavity, theplurality of glass spheres defining interstitial spaces therebetween; acoating material disposed at least partially on outer surfaces of theplurality of glass spheres, wherein the plurality of glass spheres andthe coating material define an adhering base material; and asilica-based material disposed on at least a portion of the adheringbase material, wherein the coating material and the silica-basedmaterial occupy substantially all of an interstitial volume defined bythe interstitial spaces.
 2. The insulated structure of claim 1, whereinthe coating material is a functional group material.
 3. The insulatedstructure of claim 2, wherein the functional group material definesmagnetic characteristics of the plurality of glass spheres to definepositively charged glass spheres, and wherein the silica-based materialis negatively charged and adheres to the positively charged glassspheres.
 4. The insulated structure of claim 2, wherein the functionalgroup material is at least one of an amine functional group, a silanolfunctional group, and a silane functional group.
 5. The insulatedstructure of claim 1, wherein the coating material is a binder material.6. The insulated structure of claim 5, wherein the binder materialgenerates adhesive surfaces of the plurality of glass spheres, and thesilica-based material adheres to the adhesive surfaces via the bindermaterial.
 7. The insulated structure of claim 5, wherein the bindermaterial includes an organic binder.
 8. The insulated structure of claim5, wherein the binder material includes at least one of cellulose, wax,polyethylene glycol, gelatin, starch, polyvinyl alcohol,polymethacrylates and sodium silicate.
 9. The insulated structure ofclaim 1, wherein the plurality of glass spheres are hollow glassspheres.
 10. The insulated structure of claim 1, wherein the pluralityof glass spheres are nanospheres.
 11. The insulated structure of claim1, wherein the inner liner and the outer wrapper define an insulatingpanel.
 12. The insulated structure of claim 11, wherein the insulatingpanel is a vacuum insulated panel.
 13. The insulated structure of claim1, wherein the silica-based material includes at least one of fumedsilica and precipitated silica.
 14. The insulated structure of claim 1,wherein the silica-based material at least partially includes perlite.15. The insulated structure of claim 1, wherein the insulating cavitydefines an at least partial vacuum.
 16. A method for forming asuper-insulating material for a vacuum insulated structure for anappliance, the method comprising steps of: disposing a process fluid ina rotating drum; disposing a silica-based material into the processfluid within the rotating drum to form a silica-based liquid; disposingglass spheres within the silica-based liquid; mixing the glass sphereswith the silica-based liquid; and removing at least a portion of theprocess fluid from the silica-based liquid, wherein the silica-basedmaterial adheres to the glass spheres to define silica-coated spheres toform the super-insulating material, wherein a surface of thesilica-coated spheres is indicative of the silica-based material. 17.The method of claim 16, further comprising the steps of: disposing asecondary insulating material into the rotating drum, whereininterstitial spaces are defined between the silica-coated spheres; andmixing the secondary insulating material with the silica-coated spheresto define the super-insulating material, and wherein the secondaryinsulating material occupies substantially all of an interstitial volumedefined by the interstitial spaces, wherein the step of removing theprocess fluid includes a chemical process, wherein a first portion ofthe process fluid is removed and a second portion of the process fluidbinds the silica-based material to the glass spheres.
 18. A method forforming a super-insulating material for a vacuum insulated structure foran appliance, the method comprising steps of: disposing a silica-basedmaterial into a mixing drum, wherein the mixing drum includes at leastone mixing impeller; disposing an opacifier into the mixing drum,wherein the silica-based material is mixed with the opacifier; disposinga granulation fluid into the mixing drum, wherein the granulation fluidis combined with the silica-based material and the opacifier; removing afirst portion of the granulation fluid from the mixing drum, wherein asecond portion of the granulation fluid bonds with the silica-basedmaterial to define a densified silica-based mixture; and conducting atleast one milling operation wherein the at least one mixing impellergranulates the densified silica-based mixture to define thesuper-insulating material.
 19. The method of claim 18, wherein the firstportion of the granulation fluid includes at least one solvent and thesecond portion of the granulation fluid includes a binding material,wherein the at least one solvent includes at least one of water, ethanoland isopropanol, and wherein the at least one solvent is removed throughevaporation.
 20. The method of claim 18, wherein the second portion ofthe granulation fluid forms polar bonds with the silica-based materialto define the densified silica-based mixture.